Collect. Czech. Chem. Commun. 1983, 48, 2977-2988

Potential antitussives: Synthesis and pharmacology of a series of 1-[2-amino-2-(4-fluorophenyl)ethyl]-4-(2-benzoylpropyl)piperazines

Zdeněk Vejdělek and Miroslav Protiva

Research Institute for Pharmacy and Biochemistry, 130 60 Prague 3


Compound V, obtained by a reaction of 2-chloro-4'-fluoroacetophenone with 1-(ethoxycarbonyl)piperazine, was reduced with sodium borohydride to the amino alcohol VIf. The hydrochloride of VIf was treated with thionyl chloride to give the hydrochloride of 1-[2-chloro-2-(4-fluorophenyl)ethyl]-4-(ethoxycarbonyl)piperazine (VIg). The crude VIg was subjected to substitution reactions with diethylamine, pyrrolidine, piperidine, morpholine and 1-methylpiperazine in benzene at 60 °C. The obtained aminocarbamates VIa-VIe were hydrolyzed with concentrated ethanolic potassium hydroxide and gave the amines VIIa-VIIe. Mannich reactions of the hydrochlorides of these compounds with paraformaldehyde and propiophenone (and 4-hydroxypropiophenone, respectively) resulted in the title compounds IIIa-IIIe, IVa,b and IVd,e. Only substances IIIa and IIId were found to have an antitussic activity in rats and guinea-pigs comparable to that of eprazinone (I). In higher doses they brought about central depression, ataxia and ptosis in mice and some of them adrenolytic and hypotensive effects in rats.